Many integrated circuit (“IC”) packages include a single IC die mounted on a leadframe or other conductive substrate to which the IC die is electrically connected. The die is a small semiconductor block that contains a circuit that performs a predetermined function. The leadframe or other electrical substrate enables the circuit in the die to be connected to external circuits which are typically provided on a printed circuit board or other electrical assembly to which the IC package is electrically attached. The IC package generally also includes a layer of hard, nonconductive encapsulating material which protects the die and electrical substrate.
IC dies contain active circuit elements, such as transistors, that act on a signal input to the die. It is sometimes desirable to pass a signal through passive circuit elements such as resistors and capacitors either before the signal is input to the die or after the signal leaves the die. One way to do this is to provide one or more passive circuit elements within the IC package. The passive circuit elements might be, for example, an etched or plated metal circuit layer or a discrete circuit device attached to the die.